Arrangement in electrical air blast circuit breakers



Feb. 20, 1951 H. FORWALD ARRANGEMENT IN ELECTRICAL AIR BLAST CIRCUIT BREAKERS Filed Jan. 17, l948 e'x/Mrs a/s/r/xva c/m/vaaes 5/ /forn e y,

Patented Feb. 20, 1951 ARRANGEMENT IN ELECTRICAL AIR. BLAST CIRCUIT BREAKERS Haakon Forwald, Valhalla, Ludvika, Sweden, assignor to Allmanna Svenska Elektriska Aktiebolaget, Vasteras, Sweden, a Swedish corporation Application January 17, 1948, Serial No. 2,925'

In'Sweden Ziune13, 1946' Section 1, Public Law 69 ,,-Aug;ust,8, 1946 Patent expires June'13, 1966 6 Claims. 1

This invention relates to an arrangement in electrical air blast circuit breakers.

In large air blast circuit breakers a large quantity of compressed air under high pressure is necessary to accomplish the extinction of the are or arcs, and the air blast valve for the control of the air is therefore very large and requires a considerable force for its operation, due to the unbalanced force exerted on the valve disc by the compressed air. The present invention has for its object to provide an arrangement for, facilitating the operating of the air blast control system. The invention consists in dividing the commonly used single air blast valve into two air valves and in so arranging such valves that when one of them is opened by a force counteracting the unbalanced force from the compressed air, the air escaping through this valve will aid in opening the other valve by counteracting the unbalanced force from the compressed. air on the disc of this valve.

The invention is hereinafter described with reference to the accompanying drawing which shows a control valve system for a three phase air blast switch.

4 Oiithe dra'wing, l designates the extinguishing chambers of the switch, 2 is a compressed air container, and 3 is a conduit for the delivering of compressed air to the extinguishing chambers. The conduit 3 may, by means of the disc valves 4, be brought into communication with the interior of the compressed air container 2. These valves 5, are provided with valve discs 4, 5 respectively, and are operated by pistons G, a movable in operating cylinders 8, 9,

respectively. The valves 4, 5 are held in their closed position by springs ii, I2 acting on the pistons 6 and l', and are operated by means of an operating valve it giving access of compressed air from the container 2 to the cylinders 8 and 9.

In operation, when the valves Al, 5 are closed the air in the container exerts a considerable force on the upper side of the discs 4 and 5 and together with the springs l 5, i2 forces said valves against their seating, the lower sides of the discs being exposed to atmospheric pressure. When the valve 53 is opened the lower sides of the pistons 6, l are exposed to the pressure in the con-- tainer 2 and the valves 4, 5 are opened since the force exerted by the pistons on the discs 4, is greater than the force exerted downwardly on the discs by the springs and by the air in the container.

The advantages of the invention are clear from the following facts. The opening area of a valve is'the product of the circumference of the valve disc and the distance between the valve seat and the disc when in the opened position. This area is thus proportional to the diameter of the valve disc. The force necessary for operating the valve disc, however, is proportional to the square of the valve disc diameter. When two smaller valves are used instead of a single valve, the diameter of the smaller valve discs for the same total valve opening need only be half the diameter of the single valve disc. The force actuating the smaller valve discs will be, for each valve, only one-fourth of that necessary for the single valve disc and thus the total force neces sary for the two small valves need be only onehalf of that for a single valve. It is thus obvious that, when two valves are provided, a con" siderable gain is effected in the size of the operating cylinders. Instead of making the two valve discs considerably smaller than the single valve disc with corresponding gain in the operating force, this gain may be sacrificed, and instead, the stroke of the valve discs may be shortened. For the same total valve opening a more rapid action is thus obtained with two valves than with a single valve.

The invention has the further important ad- Vantage that if one valve should stick, the air escaping through the other valve into the conduit 3 would aid in opening the first valve by exerting pressure on the underside of the disc 4 or 5.

I claim as my invention:

1. Control means for the delivery of compressed air to the extinguishing chambers of electric circuit-breakers, comprising at least two valves for controlling the flow of compressed air to the said chambers, and means providing uninterrupted air communication between said valves on their outlet sides.

2. Control means for the delivery of arc extinguishing air individually to the difierent phases of an electric circuit breaker, comprising a plurality of valves controlling the flow of air, and a common chamber providing uninterrupted air communication between the valves on their outlet sides.

3. Control means for the delivery of compressed air to the extinguishing chambers of a plurality of breaking poles of an electric circuit breaker, comprising means for conducting air to all the chambers, at least two valves for the control of the air to all said chambers, and a common air chamber providing free communication between the outlet sides of said valves.

4. Control means according to claim 1 comprising a common pilot valve controlling the operation of said valves.

5. Control means for the delivery of compressed air individually to the extinguishing chambers of different phases in electric circuit-breakers, comprising a plurality of valves controlling the delivery of air, means providing free communication between the outlet sides of the difierent valves, and a valve controlling pilot valve for said delivery valves.

6. An electric air blast circuit breaker comprising are extinguishing chambers, an extinguishing air pipe line common for all the extinguishing chambers, a common compressed air magazine for said extinguishing chambers, at least two air valves each providing independent communication between said air magazine and said pipe line, and means for operating said valves.

HAAKON FORWALD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

